In recent years, according to demands for refining and sophisticating a semiconductor device, a low dielectric constant film (hereafter denoted as a low-k film) is used as an interlayer insulating film. A patterning using an RIE (Reactive Ion Etching) is performed on such a low-k film, and after a wet processing, a barrier metal/Cu seed spattering, a Cu plating, a CMP (Chemical Mechanical Polishing) are sequentially performed, thereby a metal wiring layer such as a via, a line and the like is formed.
In such a metal wiring layer, there is a problem that a stress migration defect (hereafter denoted as an SM defect) is generated therein, and reliability and yield of the semiconductor device is decreased. The SM defect is a phenomenon in which the metal wiring layer is disconnected by heat or mechanical stress even if no current is flowing in the metal wiring layer.